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Magnetism
Putting “Magnetism” in Recognizable terms: Magnetism is the product of attractive and
repulsive forces in a material (usually cobalt, nickel, or iron). These magnetic forces are similar to
electrical forces as they can attract or repel without touching an object and the strength of the forces
depends on the distance of separation.
Putting “Magnetism” in Conceptual terms: Magnets have poles or locations on the magnet
where the attractive or repulsive forces are stronger. If a bar magnet where to be suspended from a
string, one pole would point to the earth’s magnetic north or be “north-seeking”, while the other
would point to the earth’s magnetic south or be “south-seeking”. This is why a magnet’s ends are
labeled with a North and South Pole. Holding two magnets next to each other, the north pole would
be attracted to the south pole, but it would repel against another north pole. So, opposite poles
attract, but like poles repel.
If a bar magnet was broken in half, it would create two magnets each with their own north
and south pole. If the process continued, breaking each magnet in half until it reached the size of
one atom, the atom would have a north and south pole. This demonstrates that atoms themselves
can be a magnet.
If an atom can be a magnet then what causes magnetism? The answer is electrons in motion.
Electrons in an atom are in constant motion, which creates a tiny electrical current (negative
charges flowing in one direction). These tiny electrical currents can produce tiny magnetic fields.
(Magnetic fields are areas surrounding a magnetic, often invisible to the naked-eye, influenced by
the attractive or repulsive forces of the magnet.) If two electrons are moving/spinning in the same
direction they can create a stronger or greater magnetic field, but if two electrons are
moving/spinning in opposite directions they can cancel out each other’s magnetic fields out. Most
materials contain electrons that spin in opposite directions. Iron, nickel, and cobalt are the
exceptions. They contain electrons that spin in similar directions allowing them to be magnetized.
The more their electrons become aligned the stronger the magnet they become. (see diagram)
Putting “Magnetism” in Process terms: Magnetism can be changed by altering the alignment of
the magnetic domains. Magnetic domains are clusters of atoms/electrons aligned within a material.
If a bar magnet is dropped or heated, some of the magnetic domains or atoms/electrons shift out of
alignment weakening the magnetic forces. However, if a bar magnet or iron bar is stroked by a
stronger magnet the atoms/electrons can be coaxed into alignment. Another way to strengthen or
create a magnet is by using an electric current. In an electric current the electrons or negative
charges flow in one direction causing the atoms to become aligned which as stated earlier causes
magnetism. Theses types of magnets made from an electric current are known as electromagnets
and a prime example is a junkyard crane sorting scrap metal.
Putting “Magnetism” in Applicable terms: The compass is the simplest application of magnetism
as it orients itself to earth’s magnetic field. As electric currents are used to create magnets, so
magnets can be used to create electricity. So, magnets are found in electric motors, generators, and
integral components of most all electronic devices. One of their newest function is to reduce friction
as in monorail trains. They use repulsive magnetism to lift the train from the surface of the rail
allowing the train to move at high speeds.
Attachments:
I_Sci_004_Magnetism_I_Diagrams.doc
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